Refrigerant mixture comprising difluromethane,...

Details Refrigerant mixture comprising difluromethane,... Refrigerant mixture comprising difluromethane,...

2000-11-09

2003-02-25

Hardee, John (Department: 1751)

Compositions

Vaporization, or expansion, refrigeration or heat or energy...

Reexamination Certificate

active

06524495

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigerant mixture which is useful as a substitute for chlorodifluoromethane (CHCIF
2
, HCFC-22). More particularly, the present invention relates to a refrigerant composition which is useful as a substitute for HCFC-22, which comprises a first constituent of difluoromethane (CH
2
F
2
, HFC-32); a second constituent of pentafluoroethane (CHF
2
CF
3
, HFC-125); a third constituent of 1,1,1-trifluoroethane (CH
3
CF
3
, HFC-143a); a fourth constituent selected from the group consisting of cyclopropane (C
3
H
6
, RC-270), 1,1,1,2,3,3,3-heptafluoropropane (CF
3
CHFCF
3
, HFC-227ea), 1,1,1,2,2-pentafluoropropane (CH
3
CF
2
CF
3
, HFC-245cb), isobutane (CH(CH
3
)
2
CH
3
, R-600a), octafluorocyclobutane (C
4
F
8
, RC-318), 1,1,1,2,3,3-hexafluoropropane (CHF
2
CHFCF
3
, HFC-236ea), butane (C
4
H
10
, R-600), bis(difluoromethyl)ether (CHF
2
OCHF
2
, HFE-134) and pentafluoroethylmethylether (CF
3
CF
2
OCH
3
, HFE-245).
2. Description of the Background Art
As is well known, CFC compounds have been restricted in production and use in accordance with the Montreal Protocol because they have been found as a main factor in contributing to the destruction of the ozone layer. In advanced nations, the use of such CFC compounds has already been banned since 1996. It is also known that HCFC-based compounds such as HCFC-22 have considerable effects in causing damage to the ozone layer even though this effect is less severe than those of the CFC compounds. For this reason, a restriction has been made to gradually reduce the use of such HCFC-based compounds. A plan has also been made to ban the use of HCFC-based compounds about the year 2020.
This has resulted in a number of world-wide research efforts to produce substitute materials coping with the restriction in use of HCFC-22 which will be more severe in the future. The representative examples of a substitute refrigerant mixtures are HFC-407C and HFC-410A proposed by the American Society of Heating. Refrigerating and Air-Conditioning Engineers (ASHRAE). HFC-407C is a refrigerant mixture of HFC-32/125/134a in a ratio of 23/25/52 (based on weight percent). Meanwhile, HFC-410A is a refrigerant mixture of HFC-32/125 in a ratio of 50/50 (based on weight percent).
In addition, U.S. Pat. No. 5,080,823 discloses a mixed refrigerant composition of HFC-143a/opropane (C
3
H
8
), U.S. Pat. No. 5,185,094: HFC-32/125/134a, U.S. Pat. No. 5,211,867: HFC-125/143a, U.S. Pat. No. 5,234,613: HFC-32/propane, U.S. Pat. No. 5,236,611: PFC-218/ HFC-143a, U.S. Pat. No. 5,290,466: HFC-32/134a/134, U.S. Pat. No. 5,340,490: HFC-23/CO
2
or HFC-23/116/CO
2
, U.S. Pat. No. 5,403,504: HFC-125/32, U.S. Pat. No. 5,429,760: HFC-23/134a, U.S. Pat. No. 5,538,660: HFC-32/HFC-134a/FC-14 or HFC-32/HFC-134a/PFC-218, and U.S. Pat. No. 5,643,492: HFC-32/125/134a.
Also, Japanese Patent Laid-open Publication No. 172386/1991 discloses a mixed refrigerant composition of HFC-32/125/152, Japanese Patent Laid-open Publication No. 170594/1991: HFC-23/125/134a, Japanese Patent Laid-open Publication No. 170592/1991: HFC-32/143a/152a, Japanese Patent Laid-open Publication No. 170593/1991: HFC-23/125/32, Japanese Patent Laid-open Publication No. 170591/1991: HFC-23/143a/134a, Japanese Patent Laid-open Publication No. 170590/1991: HFC-125/134a/32, Japanese Patent Laid-open Publication No. 170589/1991: HFC-23/143a/152a, Japanese Patent Laid-open Publication No. 170588/1991: HFC-125/143a/134a, Japanese Patent Laid-open Publication No. 170587/1991: HFC-32/134a/152a, Japanese Patent Laid-open Publication No. 170586/1991: HFC-32/143a/134a, Japanese Patent Laid-open Publication No. 170585/1991: HFC-32/125/134a, Japanese Patent Laid-open Publication No. 170584/1991: HFC-23/134a/152a, Japanese Patent Laid-open Publication No. 170583/1991: HFC-125/143a/32, Japanese Patent Laid-open Publication No. 222893/1992: HFC-132/152a, Japanese Patent Laid-open Publication No. 154887/1992: HFC-134/152a , Japanese Patent Laid-open Publication No. 117645/1993: HFC-23/134a/propane, Japanese Patent Laid-open Publication No. 117643/1993: HFC-125/134a/propane, Japanese Patent Laid-open Publication No. 65561/1994: HFC-23/152a/PFC-218, Japanese Patent Laid-Open Publication No. 128872/1994: HFC-32/PFC-218, Japanese Patent Laid-Open Publication No. 220433/1994: HFC-32/125/RC-318, Japanese Patent Laid-Open Publication No. 173462/1995: HFC-143a/125/134a/heptane (C
7
H
16
), Japanese Patent Laid-open Publication No. 176537/1996: PFC-218/RC-270/HFC-152a, Japanese Patent Laid-open Publication No. 151569/1996: propane/RC-270/HFC-34a, Japanese Patent Laid-open Publication No. 127767/1996: HFC-32/134a/RC-318, Japanese Patent Laid-open Publication No. 25480/1997: HFC-32/134a/125/isobutane, Japanese Patent Laid-open Publication No. 59611/1997: HFC-134a/isobutane, Japanese Patent Laid-Open Publication No. 208941/1997: HFC-32/152a/125/RC-270, and Japanese Patent Laid-open Publication No. 21664/1997: HFC-125/143al134a/RC-270.
Also, Korean Patent Publication No. 93-10514 (Application No. 90-19594) discloses a mixed refrigerant composition of HFC-23/132/152a, HFC-23/125/152a, HFC-32/143a152a, HFC-125/143a/152a, HFC-32/125/125a, HFC-23/143a/152a, or HFC-23/125/152a, Korean Patent Publication No. 93-10515 (Application No. 90-19596): HFC-23/32/134, HFC-23/32/134a, HFC-23/125/134a, HFC-23/125/134, HFC-32/125/134, HFC-23/143a/134a, HFC-32/125/134a, HFC-125/143a/134a, or HFC-125/143a/134, Korean Patent Laid-Open Publication No. 96-4485 (Application No. 95-21221): HFC-32/23/134a, Korean patent Laid-open Publication No. 95-704438 (Application No. 95-701865): HFC-32/125/134a, Korean patent Laid-open Publication No. 96-701168 (Application No. 95-704038): HFC-227ea/HFC-152a, and Korean Patent Laid-open Publication No. 97-704853 (Application No. 97-700436): HFC-134a/HCFC-124/butane.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a novel refrigerant mixture which is useful as a substitute for HCFC-22. That is, the present invention has an object to provide a refrigerant composition produced by mixing additionally one component of RC-270, HFC-227ea, HFC-245cb, R-600a, RC-318, HFC-236ea, R-600, HFE-134 and HFE-245 with a mixture of HFC-32, HFC-125 and HFC-143a, thereby producing a composition capable of exhibiting properties similar to HCFC-22.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to a refrigerant composition which is useful as a substitute for HCFC-22, which comprises a first constituent of difluoromethane (CH
2
F
2
, HFC-32); a second constituent of pentafluoroethane (CHF
2
CF
3
, HFC-125); a third constituent of 1,1,1-trifluoroethane (CH
3
CF
3
, HFC-143a); a fourth constituent selected from the group consisting of cyclopropane (C
3
H
6
, RC-270), 1,1,1,2,3,3,3-heptafluoropropane (CF
3
CHFCF
3
, HFC-227ea), 1,1,1,2,2-pentafluoropropane (CH
3
CF
2
CF
3
, HFC-245cb), isobutane (CH(CH
3
)
2
CH
3
, R-600a), octafluorocyclobutane (C
4
F
8
, RC-318), 1,1,1,2,3,3-hexafluoropropane (CHF
2
CHFCF
3
, HFC-236ea), butane (C
4
H
10
, R-600), bis(difluoromethyl)ether (CHF
2
OCHF
2
, HFE-134) and pentafluoroethylmethylether (CF
3
CF
2
OCH
3
, HFE-245).
It is preferred that the refrigerant composition of the present invention comprises a first constituent of 15 to 95% by weight difluoromethane (CH
2
F
2
, HFC-32); a second constituent of an amount up to 60% by weight pentafluoroethane (CHF
2
CF
3
, HFC-125); a third constituent of an amount up to 70% by weight 1,1,1-trifluoroethane (CH
3
CF
3
, HFC-143a); a fourth constituent of an amount up to 50% by weight comprising one selected from the group consisting of cyclopropane (C
3
H
6
, RC-270), 1,1,1,2,3,3,3-heptafluoropropane (CF
3
CHFCF
3
, HFC-227ea), 1,1,1,2,2-pentafluoropropane (CH
3
CF
2
CF
3
, HFC-245cb), isobutane (CH(CH
3
)
2
CH
3
, R-600a), octafluorocyclobutane (C
4
F
8
, RC-318), 1,1,1,2,3,3-hexafluoropropane (CHF
2
CHFCF
3
, HFC-236ea), butane (C
4
H
10
, R-600), bis(difluoromethyl)ether (CHF
2
OCHF
2
, HFE-134) and pentafluoroethylmethylether (

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